\documentclass[a4paper, reqno, oneside]{book}
  \usepackage[13pt]{vnextsizes}
\usepackage{amsmath,amsxtra,amssymb,latexsym, amscd,amsthm}
\usepackage{graphicx}
\usepackage{indentfirst}
\usepackage{color}
\usepackage[utf8]{vietnam}
\usepackage{amsmath}
\usepackage[mathscr]{eucal}
\usepackage{amsfonts}
%\input setbmp
\usepackage[unicode]{hyperref}
\usepackage{titledot}
\titlename{Chương}
%+ Can le van ban

\setlength{\oddsidemargin}{0in}
\setlength{\textwidth}{6.truein}
\setlength{\topmargin}{-0.5truein}
\setlength{\textheight}{9.3truein}
%\renewcommand{\baselinestretch}{1.3}
\usepackage{mathptmx}
%+ Dinh nghia mot so ky hieu toan hoc.
\newtheorem{remark}{\bf Chú ý}[section]
\newtheorem{example1}{\bf Ví dụ}[chapter]
\newenvironment{example}{\begin{example1}}{\end{example1}}
\newtheorem{prof}{}
%+ Bat dau tai lieu tai day.
 \usepackage[usehighlevels]{alnumsec}

\begin{document}

\alnumsecstyle{Raaa}
\surroundRoman{}{}
\surroundarabic[(][)]{.}{}
%+ ==============================================
% \makeatletter
% \renewcommand{\ps@myheadings}{
% \renewcommand{\@oddhead}{\textsf{Khóa luận tốt nghiệp - ngành toán tin ứng dụng}\hfil\textrm{\thepage}}
% \renewcommand{\@oddfoot}{\textsf{Nguyễn Thị Xuyên, Lớp K49A2, Toán tin ứng dụng}\hfil}
% }
% \makeatother 

\newpage
\input bialuanan
%+ Page style
\pagestyle{plain}
\input loicamon
\tableofcontents
\newpage
\input loinoidau
\newpage
\input chuong1
\input chuong2
\input chuong3
%\newpage
%\input{Phuluc}


\newpage
\input ketluan

%+ Tai lieu tham khao
\newpage
\input tailieuthamkhao

\end{document}